The Eocene represents the last greenhouse interval before Present. The maximum warming during the early Eocene was followed by a long-term cooling trend culminating in the Antarctica glaciation at the base of the Oligocene. Superimposed on this long-term cooling trend there is a prominent transient warming event known as the middle Eocene climatic optimum (MECO) occurring during the early Bartonian. The carbonate ramp succession cropping out in the Argentina Valley (Maritime Alps) offers new insights on the evolution of shallow water realms during this time interval. This ramp displays two main facies belts, middle and outer ramp. The middle ramp is recorded by larger benthic foraminifer floatstone to rudstone, passing to Solenomeris branches and nodule floatstone to rudstone evolving to branching coralline algal floatstone. The outer ramp is dominated by bioturbated marly wackestone to packstone alternating with larger benthic foraminifer floatstone with a silty matrix. The investigated ramp was affected by continuous dispersion and reworking of the skeletal components as other Tethyan Eocene ramps. During the Eocene, the Alpine foreland was influenced by fine terrigenous input controlling the trophic conditions and promoting seawater stratification and the development of a strong pycnocline, for which many perturbations could propagate as internal waves. The reworking of skeletal components of the ramp has been ascribed to the action of internal waves. The switch of carbonate production from a carbonate factory dominated by larger benthic foraminifera to a factory in which the encrusting foraminifer Solenomeris was the main carbonate producer biota, is indicative of a radical change in palaeoenvironmental conditions affecting the early Bartonian. The acme of Solenomeris often coincided with the crisis of carbonate producers during intervals of an evident deterioration of environmental conditions. In this case the acme is probably related to the adverse conditions linked to the (MECO) warming event. Finally, the drowning of the nummulitic ramp has been caused by light reduction for the photo-dependent biota due to progressively increasing depth linked to flexural subsidence of the foreland plate, and minor efficiency of the aphotic carbonate factory.

中文翻译：

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MECO 和高山造山作用：阿根廷山谷（利古里亚阿尔卑斯山）巴托尼麻石和 Solenomeris 石灰岩相演化的制约因素

始新世代表现在之前的最后一个温室间隔。始新世早期的最大变暖之后是长期降温趋势，最终在渐新世底部的南极冰河作用中达到顶峰。叠加在这种长期降温趋势之上的是一个突出的瞬时变暖事件，称为中始新世最佳气候 (MECO)，发生在巴托阶早期。在阿根廷山谷（滨海阿尔卑斯山）出现的碳酸盐斜坡序列提供了有关此时间间隔内浅水区演化的新见解。该斜坡显示两个主要相带，中间斜坡和外斜坡。中间斜坡由较大的底栖有孔虫浮石记录到砂石，传递到Solenomeris分支和结节浮石到粉石演变成分支珊瑚藻浮石。外部斜坡主要是生物扰动的泥灰质泥灰岩，与具有粉质基质的较大底栖有孔虫浮石交替。与其他特提斯始新世斜坡一样，所研究的斜坡受到骨架成分的连续分散和再加工的影响。在始新世，高山前陆受到细小的陆源输入的影响，控制了营养条件，促进了海水分层，形成了强烈的后斜斜，许多扰动可以作为内波传播。斜坡骨架组件的再加工归因于内波的作用。Solenomeris是主要的碳酸盐生产生物群，表明影响早期巴顿纪的古环境条件发生了根本性变化。在环境条件明显恶化的间隔期间，Solenomeris的顶峰经常与碳酸盐生产商的危机同时发生。在这种情况下，顶点可能与与（MECO）变暖事件相关的不利条件有关。最后，由于与前陆板块弯曲下沉相关的深度逐渐增加，以及无光碳酸盐工厂的小效率，光依赖生物群的光减少导致了nummulitic斜坡的淹没。